The present invention relates to a mechanism for adjusting the size of an aperture. This adjustable aperture mechanism may be used to control the flow of light, gas, or fluid, or it may be used as a collet or chuck to hold a solid object in place.
In target shooting, an adjustable aperture is desirable, because it allows the shooter the ability to fine tune his or her sight picture for optimum performance. Until now, the only way to change aperture diameters for an AR-15/M-16 service rifle was to use a system consisting of interchangeable fixed diameter inserts. This system is slow and tedious to use, prone to inadequate adjustment, and is prone to the loss of individual parts.
The present invention provides a tapered hole, an O-ring located in the tapered hole, and a pusher that pushes the O-ring into the tapered hole, to reduce the size of the aperture. When the pusher is retracted, the O-ring returns to its enlarged shape, enlarging the size of the aperture. This mechanism permits periodic or continuously-variable control of the size of the aperture by adjusting the position of the pusher.